1. Field of the Invention
The present invention relates to a gas discharge display device, and more particularly to a gas discharge display device as represented by a plasma display device incorporating a PDP (Plasma Display Panel).
PDPs are becoming more and more popular as a means for television display on a large screen since their practical application to color display started. One of the problems related to image quality of PDPs is an enlargement of a reproducible color range.
2. Description of the Related Art
AC-type PDPs with a three-electrode surface-discharge structure have become commercialized as color display devices. The three-electrode AC surface-discharge PDPs have pairs of main electrodes arranged parallel to each other on individual lines (rows) of matrix display for sustaining light-emission, and address electrodes arranged one by one on individual columns. Ribs for preventing discharge interference among discharge cells are provided in a stripe pattern.
In the surface-discharge structure, fluorescent layers for color display can be provided on a substrate opposed to the substrate on which the main electrode pairs are placed, and thereby it is possible to prevent the fluorescent layers from being deteriorated by ion impact at electric discharges and to increase the life of the devices. A PDP having the fluorescent layers on a rear substrate is called a “reflection type”, and the one having the fluorescent layers on a front substrate is called a “projection type”. The reflection-type PDP is superior to the projection-type PDP in light-emission efficiency.
Usually, a Penning gas containing neon (Ne) mixed with a little amount (4 to 5%) of xenon (Xe) is used as a discharge gas. When electric discharge occurs among the main electrodes, the discharge gas emits an ultraviolet light, which in turn excites a fluorescent substance to emit light. Each pixel corresponds to three cells, and a display color is determined and set by controlling the amounts of light-emission of the fluorescent substances of three colors of R (red), G (green), and B (blue). Heretofore, compositions of the fluorescent substances and a ratio of light-emission intensities of the three colors have been selected so that a white display color may be obtained when the amount of light-emission of each of R, G, and B is given the same signal strength.
Here, a lot of research has been made on the composition of the discharge gas. Examples of known discharge gases include a three-component gas containing the above-mentioned Penning gas mixed with helium (He) or argon (Ar) (Ne+Xe+He, Ne+Xe+Ar), a two-component gas containing helium and xenon (He+Xe), and a three-component gas containing helium, argon, and xenon (He+Ar+Xe).
As described above, since the fluorescent substance is allowed to emit light by gas discharge in PDPs, a problem arises such that the color emitted from the discharge gas is mingled with the color emitted from the discharge gas.
FIG. 12 is a view showing an emission spectrum of a two-component gas containing neon and xenon. In FIG. 12, examples of emission peaks of R, G, and B fluorescent substances are shown by broken lines. As will be understood from FIG. 12, the emission peak of the discharge gas is located near the maximum emission peak (590 nm) of the R fluorescent substance. Therefore, the red color generated by light-emission of the discharge gas is added irrespective of the color reproduced by the fluorescent substances, whereby a reddish display will appear on the entire screen. In other words, the capability of displaying the blue and green colors will decrease. The display color of a white pixel will be a color having a lower color temperature than the color reproduced by the fluorescent substances of the three colors.